Device for transferring heat

ABSTRACT

The invention relates to a device for transferring heat and especially an evaporator, especially for the air-conditioning system of a vehicle comprising at least one collecting tank comprising at least two collecting chambers.

The invention relates to a device for transferring heat, and inparticular to an evaporator, in particular for a vehicleair-conditioning system, having at least one header which includes atleast two manifold chambers. Although the invention is described belowwith reference to the evaporator of a vehicle air-conditioning system,it should be noted that this intended use is not to be understood asconstituting any restriction, but rather the heat exchanger according tothe invention can also be used in other air-conditioning systems andother similar applications.

Devices of the abovementioned type for transferring heat are known fromthe prior art. DE 198 26 881 A1 has disclosed a heat exchanger which hasa header formed from sheet metal by shaping a prepared metal plate. Theheader is divided in the longitudinal direction into two chambers, withthe ends of two rows of flat tubes arranged one behind the otherinserted into the base of the header and air that is to be cooledflowing through the flat tubes. The manifold chambers have side walls,the adjacent side walls of the two manifold chambers being orientedparallel to one another and bearing directly against one another, wherethey are soldered to one another and to the base in order to ensure thatthe header is leaktight.

DE 100 56 074 A1 has disclosed a heat exchanger in which the connectionflanges are not, as is otherwise customary, arranged at the ends of theheader, but rather on a longitudinal side portion, so that a simplestructure without additional components can be realized. In a heatexchanger of this type too, the adjacent side walls of the two chambersare oriented surface-parallel to one another and are soldered to oneanother and to the base of the header.

One drawback of the heat exchangers which are known from the prior artis that it is necessary to maintain relatively tight manufacturingtolerances in order to keep scrap at a low level.

Therefore, the object of the present invention is to provide a heatexchanger in which greater manufacturing tolerances are possible.

The object of the present invention is achieved by claim 1.

Preferred refinements form the subject matter of the subclaims.

A heat exchanger in accordance with the present invention can be used inparticular as an evaporator for a motor vehicle air conditioning system.The heat exchanger comprises at least one header having at least twomanifold chambers, substantially each manifold chamber in each casebeing delimited substantially by a base means and a top part means. Thetop part means of a first manifold chamber comprises a first middle sidewall, and the top part means of the second manifold chamber comprises asecond middle side wall.

The first middle side wall is arranged adjacent to the second middleside wall at least over a section.

At least over part of a height of the manifold, a lateral distancebetween the first middle side wall and the second middle side wallincreases with the height above the base means.

The heat exchanger according to the invention has numerous advantages.

On account of the fact that the header has at least two manifoldchambers, which are arranged next to one another at least over asection, it is possible to provide a two-row evaporator, with the airwhich passes through the evaporator first of all passing by a first rowof flat tubes and then passing by a second row of flat tubes.

Each manifold chamber is delimited by the base means and by a top partmeans; in this context, the term “top part means” is to be understood asmeaning the boundary of the manifold chamber above the base means. Thetop part means may comprise one or two side walls and a covering wall oralso one continuously curved (e.g. semicircular) wall or the like.

A gap which widens from the base means is achieved by virtue of the factthat the manifold chambers are arranged next to one another and the“middle” side walls, i.e. the right-hand side wall of the left-handmanifold chamber and the left-hand side wall of the right-hand manifoldchamber, are at an increasing lateral distance starting from the basemeans.

This produces better flux transport and consequently better activationof the solder in the gap and therefore at the middle side walls and basemeans when the header is being soldered.

In the present context, the term “middle” side walls is to be understoodas meaning the side walls lying next to one another (also “contact sidewalls”, since they are virtually or possibly even partially in contactwith one another) of the first and second manifold chambers.Accordingly, in the case of a two-chamber manifold, the outer side wallsare the side walls on the outer side, i.e. the side walls which do nothave a manifold chamber arranged next to them. If a header has threemanifold chambers, both side walls of the manifold chambers in thecenter are what are described as “middle” side walls, since they eachhave a further manifold chamber arranged adjacent to them.

A gap which is to narrow toward the base means, in particular during thewarm-up phase, promotes the flux transport during soldering inwardtoward the base means. With conventional, i.e. parallel, side walls, thedistance between the parallel walls has to be very accuratelymaintained, since the distance influences the capillary effect.

With a heat exchanger according to the invention, the manufacturingtolerances to be maintained are lower, since the gap distance changescontinuously over the height and therefore even with relativelyinaccurate manufacturing tolerances, a gap width which has a positivecapillary effect is produced at a suitable distance.

As a result of the more favorable manufacturing tolerances, it ispossible to reduce the costs of the production process, while at thesame time achieving a lower scrap rate. Depending on the way in whichthe accuracy of the manufacturing tolerance and the costs of theproduction process are adapted to one another, it is possible to selecta low scrap rate or a scrap rate which is slightly higher than thepossible minimum, but with an overall reduction in the production costson account of the more favorable manufacturing tolerances.

In a preferred refinement of the invention, the lateral distance betweenthe first and second middle side walls or the contact side walls issubstantially V-shaped. A distance profile which increases continuouslyand strictly monotonously is advantageous since this always results in asuitable lateral distance substantially irrespective of themanufacturing tolerances.

In a further preferred refinement of the invention, at least onestability means or a distribution means is arranged on at least one sidewall. A stability means increases the stability. A distribution orstability means may be provided on a middle side wall or alternativelyalso on an outer side wall.

It is also possible for one or more distribution or stability means tobe arranged both on one or more middle side walls and/or on one or moreouter side walls. The distribution or stability means may be provided inthe interior of the manifold chambers and/or in the space outside themor may extend inside and outside the manifold chambers.

It is preferable for a longitudinal direction of at least onedistribution or stability means to be oriented substantiallyperpendicular to the base means, so that the distribution or stabilitymeans preferably extends approximately in a direction substantiallyperpendicular to the surface of the base means.

In a preferred refinement, at least one distribution or stability meansis designed as a recess means and may, for example, be formed as agroove means or notch or the like.

In this case, it is possible for the recess means to be a recess in theouter surface of a side wall of a manifold chamber which, for example,extends from the base means to a predetermined height above the basemeans. The recess means may in this case, for example, be of V-shaped orU-shaped design, in which case the width of the U, i.e. the widthbetween the limbs of the U, may be greater by a multiple than the depthof the U.

By way of example, ratios of recess width to recess height of from 1:10to 100:1 are possible, with the range from approximately 1:5 to 80:1being preferred. In the case of notch-shaped recess means, a ratio inthe region of 1:1 tends to be preferred, whereas in particular in thecase of groove-like recess means considerably greater values are alsopossible.

Recess means or stability means produced in particular, although notexclusively, by chipless production processes generally increase thestability in the lateral direction of the side walls and therefore ofthe manifold chambers as a whole.

Distribution means facilitate the distribution of the flux and of thesoldering agent.

This also produces an improved manufacturing process, since themanufacturing tolerances can be reduced while retaining the same scraprate or even achieving a lower scrap rate.

Recess means on the outer sides of the middle side walls or the contactwalls are advantageous since they ensure that a capillary gap is formedbetween the side walls or limbs of the manifold chambers, whichcapillary gap, depending on the width of the recess means, may even beof large-area form. Capillary gaps of this type, i.e. both narrow andlarge-area capillary gaps, promote the flux transport during soldering,so that a reliable soldered join can be achieved between the individualside walls and also between the side walls and the base means.

In the case of typical flat tube evaporators for the air-conditioningsystems of automobiles, the height of the recesses may be betweenapproximately 0.05 and 0.4 mm, while the width may be in the rangebetween 0.05 and 8 or 10 mm or even more. It should be pointed out atthis point that these numerical details merely relate to one specificexample. Both smaller and larger dimensions are possible with these flattube evaporators and with other flat tube evaporators, as well asevaporators in general.

In a further preferred refinement of the invention, at least onedistribution means or at least one stability means projects outward, inwhich case preferably at least one distribution or stability meansprojects outward from a side wall of at least one manifold chamber. Itis particularly preferable for at least one stability means to projectoutward on one of the middle side walls or the contact side walls, sothat the lateral distance (or gap) between the two middle side walls isreduced at the location of a stability means.

It is preferable for at least one distribution or stability means to beformed as a bead means, which is preferably produced by a chiplessroute.

It is particularly preferable for a plurality of distribution orstability means to be distributed, preferably at regular intervals, overat least one portion or even the entire length of at least one manifoldchamber, in which case the stability means may be arranged alternatelyon the outwardly facing surfaces of the middle side wall of the firstmanifold chamber and the middle side wall of the second manifoldchamber. It is also possible for all the stability means to be providedon just one middle side wall or on just one manifold chamber.

In a preferred refinement of the invention, the depth of a distributionor stability means increases at increasing distance from the base means.By way of example, the depth, i.e. the vertical distance from the outerdimension of the stability means to the side face, may be one third ofthe maximum depth in the vicinity of the base means. In the case ofoutwardly projecting stability means, this is the height with respect tothe side wall, whereas in the case of recess means as stability means,what is meant is the depth of the recess means with respect to the sidewall.

In a preferred refinement of the invention, a recess is provided in thebase means in a contact region between the middle side walls and thebase means, in which case this recess may be designed, for example, as abase bead, in order, for example, to form a guide for the ends of theside walls.

In a further preferred refinement of the invention, at least one flattube has a lower wall thickness in the region of a flank than in aregion of the rounding or of the radius.

This refinement is highly advantageous since as a result of the specialtube geometry of the flat tube with the increased radius, it is possibleto achieve a low flat tube weight combined with a high strength.

This results in a lighter tube and therefore a low overall weight. As aresult, lower total costs can also be achieved.

The wall thickness of the flat tube is preferably 10% or 20% or morelower in the region of the flanks than in the region of the radius.

The ratio of the wall thicknesses in the radius to the wall thickness atthe flank is preferably in a range from approximately 1.2 to 3 andparticularly preferably in a range between approximately 1.4 and 2.

In one configuration of the invention, the wall thickness of the flattube in the region of the flanks may be approximately 0.2 to 0.4,preferably 0.3 mm at at least one location. In particular in thisconfiguration, the wall thickness of the flat tube in the radius regionis then between 0.4 and 0.7 mm and preferably approximately 0.5 to 0.6mm at at least one location.

The fact that the wall thickness is reduced in the region of the flanksoverall saves a considerable part of the weight of the flat tubes.

In a preferred refinement of the invention, at least one top part meansis produced as a single piece, so that the middle and outer side wallsand the upper covering wall of the top part means form a single piece.

In a preferred refinement of the invention, at least one top part meansor two top part means are produced integrally as a single piece with thebase means. It is then possible, for a header which comprises twomanifold means, to produce substantially the entire header as a singlepiece from a prepared metal plate, for example by bending.

To divide the header into at least two chamber means, it is possible forthe header to be of single-part design, in such a manner that the sideelements which adjoin the base element are curved in the direction ofthe base element and are ultimately joined to one another and to thebase element.

For this purpose, it is necessary for the side elements to bepermanently joined to one another and to the base element, for exampleby soldering. By way of example, it is known for the side elements to bedesigned in such a manner that they run substantially vertically on tothe base element and can therefore be surface-soldered to one anotherand to the base element.

The base means can be prepared in such a manner that it has the desireddimensions or also the required openings or cutouts for joining to theside or top part means. Since the header can be made into its definitiveshape even before final soldering, a high strength of the means resultseven before soldering.

In a preferred refinement of the invention, at least one connectionopening for the heat transfer is arranged on a longitudinal side portionof the header, in which case it is also possible for a connectionopening to be arranged at an end side of a header or for both connectionopenings to be provided at the end sides or on one or both of thelongitudinal sides of the header.

In a preferred refinement of the invention, the header is connected totwo rows of heat transfer tubes arranged one behind the other. It isalso possible for three or even more rows of heat transfer tubes to beconnected to the header. It is preferable to provide one manifoldchamber for each row of heat transfer tubes, but it is also possible toprovide one manifold chamber for in each case, for example, two (orthree or more) rows of heat transfer tubes.

In a preferred refinement, at least one side wall is provided with atleast one tab device or the like which is fitted into cutouts in thebase means. The fitting point can in this case be jammed together. Thejamming point can also be stamped in the guide bead after the header hasbeen deformed. Jamming of the fitting point prior to soldering offersthe advantage of secure joining of the parts which are to be soldered.

It is preferable for a closure cover to be arranged at at least one andpreferably both ends of the manifold chambers.

Furthermore, it is preferable for there to be a guide bead for thepartition wall, so that the partition wall substantially cannot becometilted, resulting in improved bearing of the partition wall against theheader as a result of the U-shaped encapsulation. A U-shapedencapsulation or bead in the region of the bearing surfaces of the sidewalls or limbs also results in larger soldering surfaces.

The combination of a, for example, V-shaped gap between the inner sidewalls of the two manifold chambers and further distribution or stabilitymeans in the form of projecting beads or recesses provides the option ofa wider range of tolerances, so that in one specific example the gapdistance at the open end of the V-shaped gap can vary by up to 50%,allowing a possible fluctuation between 0.15 and 0.23 mm, while at thelower end at the base means it is between 0.05 and 0.11 mm.

The stability means ensure that there is always a sufficient capillarygap for flux transport, irrespective of manufacturing-related deviationsin shape.

Gaps which are too large or too small in conventional heat exchangersprevent the flux transport in particular in the heat-up phase, whichmeans that tighter manufacturing tolerances have to be observed or ahigher scrap rate has to be accepted.

Further advantages and possible applications of the invention aredescribed below with reference to the drawings, in which:

FIG. 1 shows a perspective view of a heat exchanger according to theinvention in accordance with a first preferred embodiment;

FIG. 2 shows a partial view of the header from the exemplary embodimentshown in FIG. 1;

FIG. 3 shows a partial view of a top part of the header shown in FIG. 2;

FIG. 4 shows the header shown in FIG. 1 in section;

FIG. 5 shows detail A from FIG. 2;

FIG. 6 shows a diagrammatic side view of part of the header of the heatexchanger shown in FIG. 1;

FIG. 7 diagrammatically depicts a second exemplary embodiment of aheader;

FIG. 8 shows a diagrammatic side view of a third embodiment of a headerof a heat exchanger;

FIG. 9 shows part of a sectional view A-A through the header shown inFIG. 8;

FIG. 10 shows a flat tube according to the invention in section; and

FIG. 11 shows a further exemplary embodiment of a heat exchangeraccording to the invention in side view.

A first exemplary embodiment of the heat exchanger according to theinvention, which is designed as an evaporator for a vehicleair-conditioning system, will now be explained with reference to FIGS. 1to 7.

The heat exchanger which is illustrated in perspective in FIG. 1comprises an upper header 2, a lower header 11 with heat transfer tubes9 arranged between them.

The upper header 2 comprises a first manifold chamber 3 and a secondmanifold chamber 4 which is parallel to it, the end sides of whichmanifold chambers are closed off by covers 5. The inlet 6 and the outlet7 for the cooling medium that is to be evaporated is provided on alongitudinal side 8 of the first header 3.

At this point, however, it should be noted that the inlet and outlet maybe provided not only on a longitudinal side 8 of one or both manifoldchamber(s) of the header 3, but rather it is also possible for the inletto be provided on a longitudinal side of the first header and the outletto be provided on a longitudinal side of the second header.

It is also possible for the inlet and outlet to be provided at the endsides of one or both manifold chambers, as illustrated in the exemplaryembodiment shown in FIG. 11, in which inlet and outlet are provided atthe end sides of the two manifold chambers of the header.

The detail illustrated on an enlarged scale in FIG. 2 illustrates thebase 12 of the header 2 and a top part 13 of the first manifold chamber3.

The top part 13 of the first manifold chamber 3, in the presentexemplary embodiment, is produced as a single piece with the base 12 ofthe header. The second top part 23 may also be produced as a singlepiece with the base 12.

The top part 13 of the first manifold chamber 3 comprises an outer sidewall 14, an upper wall 16 and a middle side wall 15, which in thepresent exemplary embodiment is arranged approximately in the center ofthe header 2.

Bending over a side edge region of the base 12 forms the top part 13having the outer side wall 14, the middle side wall 15 and the upperside wall 16, with a gradual transition between the individual wallregions. The “middle” side wall 15, which lies in the center of the base12, is in this case formed by the end of the single-piece component. Asa result of the use of auxiliary bending units 100, 100′, such aspreferably beads or stamp formations, the material can be bent moreeasily and in a more controlled way at the locations which are to bebent. In this case, it is expedient if the auxiliary bending elementreduces the wall thickness, so that the bending operation can take placemore easily at this point. According to the invention, the auxiliarybending element can be introduced into the wall from inside the headerand/or outside the header.

FIG. 2 shows that the base means and the top part means are producedfrom a single part, with auxiliary bending elements 100, 100′, 101, 101′being provided at least at locations at which the base means and the toppart means and/or the top part means and a side wall (cf. FIG. 4) adjoinone another. The auxiliary bending elements in this context are regionsof reduced wall thickness, such as preferably individual lines and/orpoints or a plurality of lines and/or points.

The wall thickness reduction produced by the auxiliary bending elementsis preferably in the range from 10% to 50% compared to the normal wallthickness. It is particularly expedient if the reduction is in the rangefrom 20% to 40% compared to the normal wall thickness.

As can be seen from FIG. 3, the end of the middle side wall 15 has tabs18 which project beyond the end of the middle side wall 15 and, duringmanufacture, can be fitted into corresponding cutouts 19 in the baseregion of the header. There, the tabs 18 are preferably jammed to thebase 12, so as to securely fix the top part 13 and the middle side wall15 to the base element 12. This ensures that the individual elements aresuccessfully and permanently soldered together, since it is impossiblefor any parts to move with respect to one another during the solderingoperation. This is also illustrated on an enlarged scale in FIG. 5.

Tube receiving parts 17 for the flat tubes 9 that are to be connectedare provided in the base 12 of the header 2.

Overflow openings 21, which allow the refrigerant to flow over from thefirst manifold chamber 3 to the second manifold chamber 4 or in thereverse direction, depending on the particular embodiment, are providedin each of the middle side walls 15 and 25 in an end region of the firstmanifold chamber 3 and the second manifold chamber 4.

FIG. 4 illustrates a side view, in section, of the header 2, with tabs18 fitted into cutouts 19 and jammed in place there, in order tofacilitate soldering, in the base 12 in the region of contact with themiddle side walls 15 and 25. The header 2 has a total height 69.

FIG. 6 illustrates a diagrammatic side view, not to scale, of thecontact region between the middle side wall 15 and the middle side wall25 and the base 12 of the header 2. Whereas a lateral distance 33 isprovided at the point of contact with the base 12, a lateral distance 32between the middle side walls is present at a height 29 above the base12.

In the exemplary embodiment, the distance 33 is provided to be 0.1 mm,and at a height 29 of approximately 10 mm the distance 32 isapproximately 0.3 mm, so that the aperture angle between the middlewalls 15 and 25 is approximately 10. The V-shaped gap 22 allows areliable capillary effect during soldering.

At the height 29 above the base means 12, a bend 10 is provided in thefirst manifold chamber 3 and a bend 20 is provided in the secondmanifold chamber 4, as can also be seen in the not so diagrammaticdrawing shown in FIG. 4. Whereas the outer side walls 14 and 24 mergeinto covering walls 16 and 26, respectively, without a discernibletransition point, in the exemplary embodiment the middle side walls 15and 25 are clearly delineated from the covering walls 16 and 26,respectively, at the bends 10 and 20.

FIG. 7 illustrates a further exemplary embodiment of a header 2, inwhich identical parts are provided with the same reference designations.This header 2 likewise comprises a first manifold chamber 3 and a secondmanifold chamber 4, which each comprise middle side walls 15 and 25,respectively.

In this exemplary embodiment, one bead 31 or a plurality of beads 31 areprovided in the V-shaped gap 22, generally arranged at regular intervalsover the length of the header 2.

The individual beads 31 may, for example, be provided only on the outerside of the middle side wall 25, but it is preferable for them to beprovided alternately on the outer side of the middle wall 15 and of themiddle wall 25. On account of manufacturing conditions, however, it isalso possible for the beads to be provided only on an outer side of onemiddle side wall (15 or 25).

The external shape of the bead 31 is substantially also V-shaped, sothat it has a lower depth, i.e. a shorter distance from the outer sideof the wall, in the region of the base 12 than in the upper region atthe distance 29 at the height of the bend 20. The dimensions of the bead31 can be adapted to the gap 22 in such a manner that the depth in thebase region is approximately 0.1 mm and the depth at the height 29 abovethe base 12 is approximately 0.3 mm. The height 59 of the bead can butdoes not have to coincide with the height 29 of the bends 10, 20.

However, other dimensions are also possible, and consequently thesenumerical details are to be understood merely as examples. Inparticular, it is possible for the dimensions of the bead to be acertain percentage smaller than the dimensions 32 or 33 which define theintended distance between the side walls 15 and 25. The beads thenguarantee a minimum distance.

In addition to the exemplary embodiment shown in FIGS. 1 to 6, theexemplary embodiment shown in FIG. 7 also provides a recess 30 of adepth 34, which in the exemplary embodiment amounts to 0.1 mm, in thecontact region between the side walls 15 and 25 and the base 12. Therecess 30 facilitates production of the header 2, since the ends of theside walls 15 and 25 are guided into the recess 30, ensuring that theyare held reliably in place, prior to the soldering operation.

The beads 31 produce large-area capillary gaps allowing a gooddistribution of the flux and of the soldering agent. Furthermore, thebeads 31 perform the function of a spacer between the outer sides of themiddle side walls 15 and 25. It is reliably ensured that the distance isnot too short to ensure a reliable soldered join.

In the exemplary embodiment shown in FIGS. 8 and 9, stability meansdesigned as grooves 35 are provided. The grooves 35 have a depth 36which in the exemplary embodiment amounts to 0.1 mm. In a similar way tothe exemplary embodiment having the beads 31 as shown in FIG. 7, so tooin the exemplary embodiment having the groove-like recesses 35 as shownin FIGS. 8 and 9, the depth of the grooves may change with the distancefrom the base 12 of the header.

In this exemplary embodiment too, the surface profiling which is formedby the grooves 35 provides the top part(s) 13 and/or 23 of the twomanifold chambers 3, 4 with stability.

The grooves 35 perform the function of distributing flux and solderingagent, so that reliable joining of the side walls 15 and 25 to the base12 is possible.

As was already the case in the previous exemplary embodiment, a recess30 is provided in the contact region between the middle side walls 15and 25 and the base 12.

FIG. 9 shows a sectional view A-A from FIG. 8.

FIG. 9 reveals the groove-like recesses 35 in plan view. In thisexemplary embodiment, the groove-like recesses 35 are arranged on bothmiddle side walls 15 and 25.

In this exemplary embodiment, the grooves have been formed bycompression of the material during the bending process for producing itsshape, so that the recesses illustrated are produced on each of theouter sides of the middle side faces.

There are a plurality of recesses, which are in this case also at thesame distance 61 from one another at the middle side walls. The recesseson the side wall 15 are laterally offset by an amount 62, whichpreferably corresponds to half the distance 61, with respect to therecesses on the side wall 25.

In the exemplary embodiment shown in FIGS. 8 and 9 too, the distance 33between the side walls in the contact region between the side walls andthe base is approximately one third of the distance at the height 29 ofthe bends 10 and 20.

FIG. 10 shows a flat tube 40 for a heat exchanger for one of theexemplary embodiments.

The flat tube has external dimensions perpendicular to the direction offlow of a refrigerant which equate to a length 41 of 30 mm and width 42of 3 mm. However, other dimensions are also possible. The wall thicknesshas a dimension 44 of 0.55 mm in the region of the radius or the roundedsections 43, whereas a considerably lower wall thickness 45 of 0.3 mm ispresent in the region of the flanks 49.

The flat tube is divided into a number of eight flow chambers over thewidth, with the middle six having an internal width of 3.2 mm. Thepartition walls 46 have a width 47 of 0.3 mm.

On account of the significantly different wall thicknesses from radiusregion to flank region, the overall result is a considerably lower totalweight of the flat tube, since there is a relatively great wallthickness in the region of the radii 43, whereas a wall thickness ofthis level is not required in the region of the flanks.

FIG. 11 illustrates a side view of a heat exchanger 60, which likewisecomprises headers 2 and 11.

Partitions 50 and 51 divide the headers 2 and 11 into a plurality oflongitudinal sections, resulting in a meandering flow path of theevaporation medium over the heat exchanger 60.

In this exemplary embodiment, the connections 6 and 7 for the inlet andoutlet are provided on the end sides of the header 2 at the manifoldchambers 3 and 4.

For details as to the further design of the heat exchanger and inparticular the design and flow ratios of the headers and the remainderof the heat exchanger, reference is made to DE 19 82 688 A1, in the nameof the present Applicant, and in particular column 1, line 1 to column6, line 16, in combination with FIGS. 1 to 6, the content of disclosureof which is hereby incorporated by reference.

Further details of the heat exchanger may also be realized in accordancewith DE 100 56 074 A1 in the name of the of the present Applicant, asdescribed in that document in column 1, line 1 to column 8, line 22 withreference to FIGS. 1 to 5, the content of which is likewise incorporatedin the content of disclosure of the present application.

1. A heat exchanger (1), in particular an evaporator for a vehicleair-conditioning system, having at least one header (2) with at leasttwo manifold chambers (3, 4), substantially each manifold chamber (3, 4)in each case being delimited substantially via a base means (12) and atop part means (13), the top part means (13) of a first manifold chamber(3) comprising a first middle side wall (15), and the top part means(23) of a second manifold chamber (4) comprising a second middle sidewall (25), the base means and the top part means being produced from asingle part, with auxiliary bending elements being provided at least atlocations in which the base means and the top part means and/or the toppart means and a side wall adjoin one another.
 2. The heat exchanger asclaimed in claim 1, characterized in that the auxiliary bending elementsare regions of reduced wall thickness, such as preferably individuallines and/or points or a plurality of lines and/or points.
 3. The heatexchanger as claimed in claim 1, characterized in that the auxiliarybending elements are introduced by stamping operations.
 4. The heatexchanger as claimed in claim 1, characterized in that the auxiliarybending elements have a wall thickness reduction in the range from 10%to 50% compared to the normal wall thickness.
 5. The heat exchanger asclaimed in claim 1, characterized in that the auxiliary bending elementshave a wall thickness reduction in the range from 20% to 40% compared tothe normal wall thickness.
 6. The heat exchanger as claimed in claim 1,characterized in that the first middle side wall (15), at least over asection, is arranged adjacent to the second middle side wall (25), alateral distance between the first middle side wall (15) and the secondmiddle side wall (25), over at least part of a height (69) of the header(2), increasing with the height above the base means (12) or remainingconstant.
 7. The heat exchanger as claimed in claim 6, characterized inthat the gap (22) between the first and second middle side walls (15;25) is substantially V shaped.
 8. The heat exchanger as claimed in claim6, characterized in that at least one stability means is arranged on atleast one side wall (14, 15; 24, 25) in order to increase the stability.9. The heat exchanger as claimed in claim 8, characterized in that alongitudinal direction of at least one stability means (31, 35) isoriented substantially perpendicular to the base means (12).
 10. Theheat exchanger as claimed in claim 8, characterized in that at least onestability means (35) is formed as a recess means (35).
 11. The heatexchanger as claimed in claim 8, characterized in that at least onestability means (35) is substantially in the form of a groove means(35).
 12. The heat exchanger as claimed in claim 8, characterized inthat at least one stability means (35) is substantially in the form of anotch (35).
 13. The heat exchanger as claimed in claim 8, characterizedin that at least one stability means (31) projects outward.
 14. The heatexchanger as claimed in claim 13, characterized in that at least onestability means (31, 35) is in the form of a bead means (31).
 15. Theheat exchanger as claimed in claim 8, characterized in that a depth (36)of at least one stability means (31, 35) increases with the distance(29) from the base means (21).
 16. The heat exchanger as claimed inclaim 1, characterized in that a base recess (30) is arranged in aregion of contact between the middle side walls (15, 25) and the basemeans (12).
 17. The heat exchanger as claimed in claim 1, characterizedin that at least one flat tube (40) has a lower wall thickness (42, 45)in the region of a flank (49) than in the region of a radius (43). 18.The heat exchanger as claimed in claim 17, characterized in that atleast one flat tube (40) has a wall thickness (45) which is at least 20%lower in the region of the flanks (49) than in region of the radius. 19.The heat exchanger as claimed in claim 17, characterized in that atleast one flat tube (40) has a wall thickness of approximately 0.3 mm atat least one location in the region of the flanks (49).
 20. The heatexchanger as claimed in claim 17, characterized in that at least oneflat tube (40) has a wall thickness (44) of approximately 0.5 mm at atleast one location in the region of a radius (43).
 21. The heatexchanger as claimed in claim 1, characterized in that at least one toppart means (13, 23) is produced as a single piece.
 22. The heatexchanger as claimed in claim 1, characterized in that at least one toppart means (13, 23) is produced as a single piece with the base means(12).
 23. The heat exchanger as claimed in claim 1, characterized inthat at least one connection opening (6, 7) is arranged on alongitudinal side section (8) of the header (2).
 24. The heat exchangeras claimed in claim 1, characterized in that the header (2) is connectedto two rows of heat transfer tubes (9) arranged one behind the other.25. The heat exchanger as claimed in claim 1, characterized in that thebase means (12) is formed out of a prepared metal plate.
 26. The heatexchanger as claimed in claim 1, characterized in that at least one sidewall (14, 15, 24, 25) is provided with at least one tab (19) which isinserted into a cutout (21) in the base means.
 27. The heat exchanger asclaimed in claim 1, characterized in that a closure cover (5) isarranged on at least one end (38) of at least one manifold chamber (3,4).
 28. The heat exchanger as claimed in claim 1, characterized in thatat least one connection opening (6, 7) is arranged at an end (38) of atleast one manifold chamber (3, 4) of the header (2).